Index: cfe/trunk/lib/Tooling/Tooling.cpp
===================================================================
--- cfe/trunk/lib/Tooling/Tooling.cpp
+++ cfe/trunk/lib/Tooling/Tooling.cpp
@@ -15,6 +15,7 @@
 #include "clang/Tooling/Tooling.h"
 #include "clang/Driver/Compilation.h"
 #include "clang/Driver/Driver.h"
+#include "clang/Driver/Options.h"
 #include "clang/Driver/Tool.h"
 #include "clang/Driver/ToolChain.h"
 #include "clang/Frontend/ASTUnit.h"
@@ -26,6 +27,7 @@
 #include "clang/Tooling/CompilationDatabase.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/Config/llvm-config.h"
+#include "llvm/Option/ArgList.h"
 #include "llvm/Option/Option.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/FileSystem.h"
@@ -241,6 +243,12 @@
     Argv.push_back(Str.c_str());
   const char *const BinaryName = Argv[0];
   IntrusiveRefCntPtr<DiagnosticOptions> DiagOpts = new DiagnosticOptions();
+  unsigned MissingArgIndex, MissingArgCount;
+  llvm::opt::InputArgList ParsedArgs =
+      driver::createDriverOptTable()->ParseArgs(
+          ArrayRef<const char *>(Argv).slice(1), MissingArgIndex,
+          MissingArgCount);
+  ParseDiagnosticArgs(*DiagOpts, ParsedArgs);
   TextDiagnosticPrinter DiagnosticPrinter(
       llvm::errs(), &*DiagOpts);
   DiagnosticsEngine Diagnostics(
Index: cfe/trunk/unittests/Tooling/ToolingTest.cpp
===================================================================
--- cfe/trunk/unittests/Tooling/ToolingTest.cpp
+++ cfe/trunk/unittests/Tooling/ToolingTest.cpp
@@ -332,6 +332,44 @@
   EXPECT_FALSE(llvm::sys::fs::remove(DepFilePath.str()));
 }
 
+struct CheckColoredDiagnosticsAction : public clang::ASTFrontendAction {
+  CheckColoredDiagnosticsAction(bool ShouldShowColor)
+      : ShouldShowColor(ShouldShowColor) {}
+  std::unique_ptr<ASTConsumer> CreateASTConsumer(CompilerInstance &Compiler,
+                                                 StringRef) override {
+    if (Compiler.getDiagnosticOpts().ShowColors != ShouldShowColor)
+      Compiler.getDiagnostics().Report(
+          Compiler.getDiagnostics().getCustomDiagID(
+              DiagnosticsEngine::Fatal,
+              "getDiagnosticOpts().ShowColors != ShouldShowColor"));
+    return llvm::make_unique<ASTConsumer>();
+  }
+
+private:
+  bool ShouldShowColor = true;
+};
+
+TEST(runToolOnCodeWithArgs, DiagnosticsColor) {
+
+  EXPECT_TRUE(runToolOnCodeWithArgs(new CheckColoredDiagnosticsAction(true), "",
+                                    {"-fcolor-diagnostics"}));
+  EXPECT_TRUE(runToolOnCodeWithArgs(new CheckColoredDiagnosticsAction(false),
+                                    "", {"-fno-color-diagnostics"}));
+  EXPECT_TRUE(
+      runToolOnCodeWithArgs(new CheckColoredDiagnosticsAction(true), "",
+                            {"-fno-color-diagnostics", "-fcolor-diagnostics"}));
+  EXPECT_TRUE(
+      runToolOnCodeWithArgs(new CheckColoredDiagnosticsAction(false), "",
+                            {"-fcolor-diagnostics", "-fno-color-diagnostics"}));
+  EXPECT_TRUE(runToolOnCodeWithArgs(
+      new CheckColoredDiagnosticsAction(true), "",
+      {"-fno-color-diagnostics", "-fdiagnostics-color=always"}));
+
+  // Check that this test would fail if ShowColors is not what it should.
+  EXPECT_FALSE(runToolOnCodeWithArgs(new CheckColoredDiagnosticsAction(false),
+                                     "", {"-fcolor-diagnostics"}));
+}
+
 TEST(ClangToolTest, ArgumentAdjusters) {
   FixedCompilationDatabase Compilations("/", std::vector<std::string>());